Study: Water temperatures off Nova Scotia will rise

A surfer tucks beneath a wave at Cow Bay in October. A recent study predicts the northwest Atlantic Ocean will warm by about three or four degrees Celsius in 60 to 100 years. (STAFF)

A new American study suggests that by the end of the century waters off Nova Scotia may be much warmer than predicted.

“We do think that this is going to be a hot spot for climate change,” said Vincent Saba, a National Oceanic and Atmospheric Administration fisheries scientist and lead author of the study.

Saba and others at NOAA’s Geophysical Fluid Dynamics Laboratory at Princeton University, N.J., used a new high-resolution global climate model to project future temperatures in the northwest Atlantic Ocean.

Their findings appear in the Journal of Geophysical Research: Oceans, published by the American Geophysical Union.

“We looked at the entire northwest Atlantic shelf. Most of the enhanced warming was right off the eastern Scotian Shelf and right off the Gulf of Maine,” Saba said Friday in an interview.

The high-resolution model more accurately simulates the circulation of the Gulf Stream and Labrador Current, said Saba, who compares it with using a new ultra high-resolution television instead of an older, standard one.

The high-resolution modelling requires about 100,000 computers to be tied together and operated for months. Not many high-resolution climate change models are used because of the high cost.

“One of the biggest problems models have for this region of the world is that it doesn’t get the Gulf Stream and the Labrador (Current) like they should,” said Saba.

“This model gets the circulation right, as opposed to the older model, so what happens is that you have global warming acting in synergy at the same time as a change in circulation.”

His model shows, with the expected rise in carbon dioxide levels, ocean temperature in the region may warm twice as fast as previously projected, and almost three times faster than the global average.

As part of predicting climate change, scientists change the concentration of atmospheric carbon dioxide in the models to calculate what happens to the ocean and air temperature.

“We basically doubled the carbon dioxide in the atmosphere <ellipsis> then we might expect to see some of these warming scenarios that we are projecting in the model.

“Off the coast of Nova Scotia and in the Gulf of Maine, you get more saltier, warmer, Gulf Stream water, which is considered subtropical water coming into the shelf. It mixes with this colder water. <ellipsis> It is like a one-two punch. You get the global warming and then you get this change in circulation, so that’s why this neck of the woods tends to warm more than the rest of the ocean.”

The study projects warming of about three or four degrees Celsius in the northwest Atlantic Ocean 60 to 100 years from now.

A study published last fall in the journal Science showed that rapid warming of Gulf of Maine waters — 99 per cent faster than other oceans — has caused a collapse of the cod fishery as it reduced their capacity to rebound from fishing. Cod are a cold-water species.

“The overarching highlight is that if these projections become a reality, then you get a greater warming off Nova Scotia, and the Gulf of Maine (and) then the impacts to fisheries and protected species will be even greater,” Saba said.

“The key message, I think, is that if you look at existing conditions and that this region has, in fact, warmed more than the global oceans, I think we should take these projections seriously.”